All three children have a their own look especially the youngest, genetics are so interesting.
Therefore I incorperated it in my studies many years ago. Unfortunately, in the end I am doing almost nothing with it these days. It is only a little bit easier for me to understand some genetic items. But as the knowledge of genetics and related developed (and still) very fast, I have missed a lot already. It is still fascinating how specific traits and/or genes can pop up generations later and/or their effect in different surroundings.
My 2 youngest nephews share some similar facial characteristics, but the eldest is very blond, blue eyes and is at about 1.90 meters of height this moment. His younger brother is currently still growing, but stays behind. Besides that he has dark hair and dark eyes. So a complete opposite with regard to colouring to his elder brother.